To generate the latent vectors, we first use an RRDBNet [1]} (denoted as \(E_0\) ) to extract features \(f_0\)  from the input LR image.
Then, we gradually reduce the resolution of the features by:
\(f_i = E_i(f_{i-1}),\quad i\in \lbrace 1, \cdots , N\rbrace ,\) 
